docs: def _get_dS2S(self, imt_per):
          """
          Table 4 of 2013 report
          """
          if imt_per == 0:
              dS2S = 0.05
          elif 0 < imt_per < 0.15:
              dS2S = self._interp_function(-0.15, 0.05, 0.15, 0, imt_per)
          elif 0.15 <= imt_per < 0.45:
              dS2S = self._interp_function(0.4, -0.15, 0.45, 0.15, imt_per)
          elif 0.45 <= imt_per < 3.2:
              dS2S = 0.4
          elif 3.2 <= imt_per < 5:
              dS2S = self._interp_function(0.08, 0.4, 5, 3.2, imt_per)
          elif 5 <= imt_per <= 10:
              dS2S = 0.08
          else:
              dS2S = 0
  
          return dS2S